Honestly, the European Knight, at it's 'max potential' WOULD win... But that's got nothing to do with the sword.
The Naginata may be effective but it's just got jack on what the halibard, with it's triple-options, could do.
The Yumi might be good but it's just not in the same league as the crossbow.
However, European knights utilized shields and developed the stirrup which allowed them to engage in mounted combat in manners that the Japanese Samurai simply could not do. Even an 'average' shield would increase the life expectancy of a knight drastically and give them a potent edge in melee combat. Combine that with full-body plate armor with it's multiple layers and so-forth and there simply isn't much comparison. Knight's have edges Samurai simply don't have. It's almost like being stuck in a massive amount of wars with soldiers coming from three continents breeds large militaristic innovations or something.
The Katana DOES have a mystique to it but it's important to understand that, at the end of the day, even if they're extremely well-forged swords, they're just swords and only part of a true soldiers kit. I actually find it really annoying that people seem to have this mental image in their heads of the European Knight being little more than a violent thug who can only swing their weapons around clumsily and whose weapons and armor are basically pool noodles and paper while a Japanese Samurai wields a blade that could sever a man in two with ease and is trained since birth to be a master of swordsmanship with no rival even possible along with three other weapon types. It's like sitting down to watch a sports game and saying one team is little more than high-schoolers drafted from the math club while the other team is international champions. Even if one team is clearly better they're both practiced and trained professionals who can hold their own.
You could argue a knight is better trained than a samurai too, both started learning from masters at about the same age, just knights fought a larger range of enemies, so had to contend with varieties in styles, while samurai mainly fought themselves.
I think it is that mysticism around most the samurai that people expect they did so much more ---